Engine design is crucial in terms of NVH. It is the sources of vibration for a vehicle. Nowadays engine tends to being smaller and less stiff and more powerful according to predecessor. Small engines with high power is inherently generates extreme force and vibrations and accordingly generates more noise. Thus engine structure and also engine main components should be designed to prevent this vibration. There are two main sources: One of them is combustion and other is inertia loads. Due to this sources engine structure can cause severe vibration and accordingly this can cause noise via transmitting it into vehicle with both structure and airborne. This paper focused on to reduce engine vibration level with changing the combustion inputs such as cylinder pressure parameters and inertia parameters like piston mass, conrod length and balancing parameters. Design of experiment is used to obtain most robust case in terms of NVH. The combination of both engine structure and combustion is chosen to reduce vibration. Accordingly the parameters are used at engine CAE model and compared with each other with performing mount vibration analysis. This powertrain analysis results are used to perform vehicle level interior noise assessment. Mount vibration analysis results are transmitted to vehicle interior with using transfer function and that allow deciding and defining best parameters in terms of customer, driver perspective. The loudness level of each parameter is compared with other cases and effects of the changes were represented.